Durham, NC -- A team led by scientists at Duke University's Pratt School of Engineering has demonstrated the first working "invisibility cloak." The cloak deflects microwave beams so they flow around a "hidden" object inside with little distortion, making it appear almost as if nothing were there at all.
Microwave cloaking isn't as shocking as optical cloaking. But it is still very impressive.
Cloaks that render objects essentially invisible to microwaves could have a variety of wireless communications or radar applications, according to the researchers.
The team reported its findings on Thursday, Oct. 19, in Science Express, the advance online publication of the journal Science. The research was funded by the Intelligence Community Postdoctoral Fellowship Program.
The researchers manufactured the cloak using "metamaterials" precisely arranged in a series of concentric circles that confer specific electromagnetic properties. Metamaterials are artificial composites that can be made to interact with electromagnetic waves in ways that natural materials cannot reproduce.
The cloak represents "one of the most elaborate metamaterial structures yet designed and produced," the scientists said. It also represents the most comprehensive approach to invisibility yet realized, with the potential to hide objects of any size or material property, they added.
Earlier scientific approaches to achieving "invisibility" often relied on limiting the reflection of electromagnetic waves. In other schemes, scientists attempted to create cloaks with electromagnetic properties that, in effect, cancel those of the object meant to be hidden. In the latter case, a given cloak would be suitable for hiding only objects with very specific properties.
I figure when the Terminator robots take over and start hunting us down the ability to hide from their microwave search beams will help some of us live longer.
The cloak passes microwaves around it unlike materials in stealth bombers that just absorb microwaves. Prevention of reflection in existing stealth technology is not as impressive as a design that keeps microwaves going on their natural course.
"By incorporating complex material properties, our cloak allows a concealed volume, plus the cloak, to appear to have properties similar to free space when viewed externally," said David R. Smith, Augustine Scholar and professor of electrical and computer engineering at Duke. "The cloak reduces both an object's reflection and its shadow, either of which would enable its detection."
The team produced the cloak according to electromagnetic specifications determined by a new design theory proposed by Sir John Pendry of Imperial College London, in collaboration with the Duke scientists. The scientists reported that theoretical work in Science earlier this year.
Are there non-military applications for this technology? If so, what are they?
|Share |||Randall Parker, 2006 October 19 09:46 PM Materials Advances|